1. Field
Aspects of the disclosure relate generally to openings for receiving fasteners and more particularly to inspection gauges therefor.
2. Background
Structural fabrication using fasteners requires matching of the fasteners and the sizes of the holes through which the fasteners are inserted. Particularly in high stress environments, proper dimensional tolerances of hole diameters during assembly are critical to assure that a selected fastener system will have desired structural properties in use. Holes may be undersize or oversize with respect to defined tolerances. In fabricating structures, such as aircraft or other complex systems where tens of thousands of fastener holes may be present, inspection of holes to assure that their dimensions are within specified tolerances can be extremely time consuming. Additionally, the repetitive nature of such measurements may require secondary indications of acceptability to assure that accuracy of inspection is maintained.
Wooden or metal dowels to be inserted into fastener holes (“go” gauges), or to be sized such that the dowels are larger than a properly sized hole (“no-go” gauges), have been used as devices for hole inspection for many years. However, a dowel having a diameter sized for no-go may often be “pushed (forced) through” a hole, deforming itself and/or the hole sufficiently to be received into the hole. Different operators exert differing amounts of force when attempting to insert a gauge into a hole. This variance can cause failed inspections. The force necessary to create “push-through” or “force-through” may not be excessive when the no-go gauge is used on a hole with a very close diameter tolerance and the dowel is accordingly sized to be only slightly larger than the hole, particularly a hole formed in soft or somewhat elastic materials.